Presently available are many commercially manufactured lock-in, lock-out power hubs for use with floating-type axles, so that power can be applied to a wheel by simply engaging or disengaging a hub clutch. However, no such device made, or presently in use, can be used with fixed live-type axles on motor vehicles.
The typical motor vehicle with two-wheel drive comes equipped with fixed live power axles in the rear and floating free-wheeling axles in the front. Exceptions to this are front-wheel drive vehicles, (example: Oldsmobile Toronado), in which case the reverse is true.
In a typical motor vehicle equipped with four-wheel drive, the front wheels have floating-type axles. The vehicle usually comes equipped with a free-wheeling lock-in, lock-out power hub or the latter can be mounted later. Inside the free-wheeling hub are spaced bearings. The bearings are on the fixed axle housing. The free-wheeling hub is held in place by nuts threaded onto the end of the fixed shaft. The outer end of the free-wheeling hub is open, and a floating axle protrudes through the opening in the wheel hub, to make it possible for lock-in, lock-out clutch hubs to be mounted. With the lock-in, lock-out hub in place, the cap can be turned so that the wheel is either powered or released for free-wheeling.
A floating axle is one in which there is an axle, within a housing, on which the wheel turns freely. This axle is readily adapted for and often comes equipped with lock-in, lock-out power hub clutches.
A fixed live axle is one to which a wheel drum is attached directly and made part of the axle. The wheel is then attached to this drum by several lug bolts, so that the power is transmitted directly to the wheels of the vehicle.
By far the greater number of vehicles travelling the highways today are equipped with fixed live drive axles almost all of which are rear end drive axles. By far the greater portion of these vehicles are equipped with automatic transmissions and for this reason it is common practice when towing such vehicles to elevate the rear end of the vehicle when towing the same. Many of these vehicles however are too large to adopt this procedure and it is necessary before towing them to have its drive shaft disengaged or removed manually before towing the vehicle.